Adaptive differential pulse code modulation system and method utilizing whitening filter for updating of predictor coefficients

Abstract

An improved technique for processing digital audio signals is provided wherein adaptation of predictor coefficients in an ADPCM environment is caused to converge in a rapid and computationally efficient manner. The technique employs a whitening filter to generate a filtered reconstructed signal which is utilized to update, or adapt, the prediction coefficients of a pole-based predictor.

Description

[0001] The present application claims the benefit of priority from U.S. Provisional patent application Ser. No. 60 / 183,280, entitled "Adaptive Differential Pulse Code Modulation System and Method Utilizing Whitening Filter For Updating Of Predictor Coefficients" filed on Feb. 17, 2000, which is incorporated by reference herein.[0002] 1. Field of Invention[0003] The present invention relates generally to encoding and decoding of digital audio signals, and more particularly to predictor adaptation in adaptive differential pulse code modulation (ADPCM) systems.[0004] 2. Description of the Prior Art[0005] FIG. 1 may be referenced in conjunction with the following discussion. ADPCM is a well-known technique for encoding speech and other audio signals for subsequent transmission over a network. A standard implementation of such a system is described in the International Telecommunication Union (ITU-T) Recommendation G.722, 7 kHz Audio-Coding Within 64 kBit / s, which is incorporated by refe...

AI Technical Summary

Problems solved by technology

Stability checking is often used to ensure that the prediction coefficients remain in desired ranges, but at the expense of increased complexity as the number of poles, i.e., coefficients, increases.

This in turn is likely to cause a distorted frequency response at the receiver 104 and its associated audio output device.

It is postulated that the Millar system and method may be computationally expensive to implement.

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